The present invention relates generally to surgical instruments and methods, and more specifically to devices and methods for surgical wound closure, tissue approximation and attachment, and vascular anastomosis, especially coronary artery anastomosis.
In coronary artery disease, one or more of the coronary arteries which supply oxygenated blood to the heart are partially or entirely blocked by a build-up of atherosclerotic plaque within the artery. This deprives the heart muscle of oxygen and nutrients, leading to myocardial infarction and even death.
Coronary artery bypass grafting remains the gold standard for the surgical treatment of severe coronary artery disease. In coronary artery bypass grafting, or CABG, a graft vessel is used to bypass a blockage in a coronary artery by connecting the distal end of the graft vessel to the coronary artery downstream of the blockage and connecting the proximal end of the graft vessel to a source of arterial blood upstream of the blockage. Various types of graft vessels may be used, including a saphenous vein taken from the patient""s leg, a radial artery removed from the patient""s forearm, oraprosthetic graft made of expanded polytetrafluoroethylene, Dacron, or other suitable material. Additionally, the left or right internal mammary arteries, which originate from the subclavian artery and reside on the top of the chest wall, may be resected at a distal location and left intact proximally, the free distal end then being connected to the diseased coronary artery downstream of the blockage. Similarly, the gastroepiploic artery, which originates from the gastroduodenal artery in the abdomen, may be resected at a distal location in the abdomen and passed into the thorax through a puncture in the diaphragm for attachment to the diseased coronary artery. Other types of graft vessels may also be used, as well as combinations of several different types of graft vessels in order to bypass multiple coronary blockages.
The surgical interconnection of two vascular structures, such as a graft vessel and a coronary artery, is a process known as anastomosis. In CABG, the anastomosis of a graft vessel to a coronary artery is particularly challenging. Several factors contribute to this challenge. First, the scale of the vessels is extremely small, the coronary arteries having a diameter on the order of about 1-5 mm, and the graft vessels having a diameter on the order of about 1-4 mm for an arterial graft such as a mammary artery, or about 4-8 mm for a vein graft. In addition, the completed anastomosis must not only provide a sealed connection and a patent blood flow path between the graft vessel and the coronary artery, but must further provide a connection which minimizes the exposure of the blood to foreign material or external vessel surfaces which can cause thrombosis at the anastomosis site. Moreover, recent studies suggests that the anastomosis site should not be dramatically different in compliance relative to either the coronary artery or the vascular graft, since such a xe2x80x9ccompliance mismatchxe2x80x9d may also cause thrombus to form at the anastomosis.
Suturing is the technique of choice for coronary anastomosis in the vast majority of CABG cases today. The anastomosis is performed by creating a small opening, or arteriotomy, in the coronary artery, and passing a series of running stitches through the walls of the graft vessel and the coronary artery, respectively, around the perimeter of the arteriotomy so as to compress the end of the graft vessel against the side wall of the coronary artery. The surgeon has a great deal of flexibility in selecting the optimum location for each stitch, based on the shape, structure and condition of the two vessels. The suture needle may be placed initially through the graft vessel wall, and, before the two vessels are closely approximated, the needle then independently placed through the desired location in the target vessel wall. The suture is then tensioned to approximate the two vessels and create a tight, hemostatic seal. The sutured anastomosis thus offers a secure, sealed and patent connection between the two vessels, while having a substantial degree of compliance due to the flexible nature of the suture material.
A drawback of the sutured anastomosis is, however, the high degree of skill, dexterity, and acute visualization required. In addition, the completion of the anastomosis takes a significant amount of time, during which the patient is maintained under cardioplegic arrest and cardiopulmonary bypass. The period of cardioplegic arrest should generally be minimized in order to minimize damage to the heart muscle. Further, in recent years, some attempts have been made at reducing the invasiveness and trauma of CABG surgery by-working through smaller incisions or xe2x80x9cportsxe2x80x9d between the ribs and using endoscopic surgical techniques. Performing microvascular anastomoses with conventional sutures is extremely difficulty when working through small ports, particularly if direct vision of the anastomosis site is not possible and reliance upon endoscopic visualization techniques is necessitated.
Various ideas have been proposed for simplifying and accelerating the process of coronary anastomosis using sutureless anastomosis devices. For example, in U.S. Pat. No. 4,350,160 to Kolesov et al., a device is disclosed for creating an end-to-end anastomosis by everting each vessel end over a split bushing and driving a plurality of staples through the everted vessel ends. For coronary anastomosis, this device requires that the coronary artery be severed downstream of the blockage and the downstream end dissected away from the surface of the heart in order to allow it to be connected end-to-end to the graft vessel. This adds an undesirable increase in time, difficulty and risk to the procedure. In addition, the staples in the Kolesov device are always positioned in a fixed pattern, allowing no flexibility in selecting the location in which each staple is to be driven through the vessels.
In U.S. Pat. No. 4,624,257 to Berggren et al., a device is disclosed for creating either end-to-end or end-to-side anastomoses. The device consists of a pair of rigid rings each having a central opening through which the end of the coronary or graft vessel may be drawn through and everted over the ring. A set of sharp pins extend outwardly from the face of each ring and pierce through the vessel wall to maintain the vessel in the everted configuration. The rings are then joined together to align the end of the graft vessel with the opening in the target vessel. While this device may be suitable for end-to-side anastomosis, eliminating the need to sever and isolate a free end of the coronary artery, the device requires that the side wall of the coronary artery be everted through the central opening of the ring, a maneuver which is likely to be extremely difficult in coronary anastomosis due to the structure and size of the coronary arteries. Moreover, the use of rigid rings that completely encircle the graft vessel and the arteriotomy creates a severe compliance mismatch at the anastomosis site which could lead to thrombosis.
An additional device which has been proposed for end-to-side anastomosis is seen in U.S. Pat. No. 5,234,447 to Kaster et al. This device consists of a rigid ring having a plurality of pointed legs extending from the ring axially in the distal direction and a plurality of angled legs extending axially from the ring in the proximal direction. The graft vessel is placed through the middle of the ring and the end is everted over the pointed legs, which puncture the vessel wall and retain it on the ring. The pointed legs are then bent outwardly, and the everted end of the graft vessel and the outwardly-oriented pointed legs are inserted through an arteriotomy in the target vessel so that the pointed legs engage the interior wall of the target vessel. The angled legs on the proximal end of the ring are then bent toward the target vessel to penetrate the outer wall thereof. While the Kaster device has a simple one-piece design and avoids the need to evert the wall of the target vessel over the device as proposed in Berggren, the device maintains a rigid ring structure which results in inadequate compliance at the anastomosis. In addition, the rigidity of Kaster""s device leaves the surgeon little flexibility in selecting the optimum location where. each leg of the device should be driven into the graft and target vessels, in contrast to the flexibility available when placing suture stitches.
U.S. Pat. No. 4,586,503 to Kirsch et al. discloses an alternative scheme for creating microvascular anastomoses. The Kirsch device consists of a plurality of individual clips each consisting of a pair of arcuate legs interconnected by a bridging section. The edges of the vascular tissue to be anastomosed are approximated and everted outwardly so that a clip can be placed over the tissue edges, and the clip is then crimped to permanently deform the. legs in an inward position. The clip thereby retains the edges of the tissue together without puncturing the tissue. A plurality of clips are placed around the graft vessel in this manner to accomplish the anastomosis. The Kirsch device eliminates the compliance problems of rigid ring-type devices, and allows the surgeon the flexibility to select the optimum location for the placement of each clip. However, the Kirsch clips suffer from several disadvantages. For example, placement of the clips while maintaining eversion and approximation of the tissue edges is difficult and time-consuming. Typically, two pairs of forceps are needed to hold the tissue edges in approximation while a third hand applies the clip, in contrast to suturing, where only one tissue edge needs to be held at one time while the suture needle is driven through it. The Kirsch clips are especially awkward in endoscopic applications, where access, visualization, and maneuverability of instruments are limited. Moreover, in end-to-side anastomosis, the tissue edges along the arteriotomy must be everted outwardly and approximated with the everted end of the graft vessel, a maneuver which becomes increasingly difficult as the ends of the arteriotomy are approached. In addition, due to variation in vessel size and structure, variation in the crimping force applied, and other factors, the clips may not reliably maintain the anastomotic connection.
In view of the foregoing, devices and methods are needed which facilitate the performance of vascular anastomosis, especially coronary anastomosis, but which eliminate the various drawbacks of prior devices. The devices and methods should allow the surgeon to select the specific locations on the graft and target vessels where the device is to be applied, similar to selecting the location of each stitch in a sutured anastomosis. The devices and methods should be relatively simple to utilize without requiring an undue degree of skill and dexterity, even at the small scale of the coronary arteries, and even in endoscopic applications. The devices and methods should be useful for performing end-to-side, end-to-end and side-to-side anastomoses. Further, the devices and methods should produce an anastomosis which is reliably sealed and patent, with a degree of compliance comparable to sutured anastomosis.
The invention provides surgical clips and methods that meet the foregoing needs, and that are useful not only for coronary anastomosis, but for anastomosis of a variety of other vascular structures, as well as in ligation, wound closure and other tissue approximation and attachment applications. The invention offers a simple and convenient solution to coronary anastomosis, allowing the anastomosis to be performed using only two hands more quickly and easily than existing devices, but with the hemostasis, patency, compliance and reliability of sutures. The devices and methods of the invention are useful not only in conventional open surgical procedures, but in endoscopic, laparoscopic, thoracoscopic and other minimally-invasive procedures as well.
In a first embodiment of the invention, a surgical clip is provided for approximating or attaching a first tissue layer to a second tissue layer. The first and second tissue layers may be any of various tissue structures, such as flaps of tissue adjacent to a wound or incision in a vessel, organ or body wall, but the invention is particularly suitable for vascular anastomosis, wherein a graft vessel is joined to a target vessel. The graft vessel has a free end and a graft vessel wall defining a graft lumen. The target vessel has a target vessel wall defining a target lumen and has an opening in the target vessel wall, which may be an incision or other opening formed in the target vessel wall (for end-to-side or side-to-side anastomoses), or an opening at a free end of the target vessel (for end-to-end anastomoses). The surgical clip includes a clip body having a distal extremity with a distal end and a proximal extremity with a proximal end. The distal end is configured to penetrate through the graft vessel wall near the free end and through the target vessel wall near the opening such that both the distal and proximal ends of the clip body are outside the graft and target vessels. At least a portion of the clip body is shapable so as to compress the graft vessel wall against the target vessel wall with the target vessel lumen in communication with the graft vessel lumen.
By penetrating the graft and target vessel walls, the surgical clip provides the long-term reliability of a sutured connection. In addition, maintaining both ends of the clip outside of both the graft and target vessels minimizes the amount of foreign material contacting blood, eliminates the need for an internal anvil which must be removed after clip application, facilitates visual confirmation of successful application of the clip, and permits manipulation of the ends of the clip to re-apply, reposition or remove the clip. Further, the surgical clip provides a reliable hemostatic seal by having a deformable portion which compresses the graft vessel wall against the target vessel wall. Moreover, through the use of a plurality of individual surgical clips, the invention provides the surgeon with the flexibility to select the ideal location on both the target and graft vessel walls to which each clip should be applied, depending upon vessel structure, condition and shape. The use of multiple independent clips also produces an anastomotic connection having compliance comparable to a sutured anastomosis.
The surgical clip may have a variety of configurations. The clip body will generally have an outer surface against which the graft and target vessel walls are compressed. In one embodiment, the proximal extremity comprises a leg extending from the clip body that is movable between an open position spaced apart from the distal extremity and a closed position closer to the distal extremity. The proximal extremity has an inner surface which faces the outer surface of the clip body in the closed position. The clip body is thus xe2x80x9cshapedxe2x80x9d by moving the proximal extremity into the closed position, thereby compressing the graft and target vessel walls between the inner and outer surfaces. The proximal extremity may be hingedly coupled to the clip body to facilitate movement thereof, but is preferably configured to be inelastically deformed from the open into the closed position.
The movable proximal extremity may also be configured to contact or to extend across the distal extremity in the closed position. In one configuration, the proximal extremity has an end portion which includes two generally parallel segments which extend across the distal extremity in the closed position and a slot between the parallel segments for receiving the distal extremity. The proximal extremity may also be configured to shield the distal end of the distal extremity in the closed position to prevent inadvertent injury to tissue. Preferably, the proximal extremity is configured to prevent its passage through the graft and target vessel walls. For example, the proximal extremity may have a cross-sectional area which is substantially larger than that of the distal extremity so that it cannot pass through the puncture created by the distal extremity. The proximal extremity may also be oriented at an angle, usually at least about 90xc2x0, relative to the distal extremity to inhibit its passage through the vessel walls.
In another embodiment, the distal extremity is movable between an open position spaced apart from the proximal extremity and a closed position closer to the proximal extremity, and the distal extremity has an inner surface which compresses the graft and target vessel walls against the outer surface of the clip body in the closed position. Preferably, the distal extremity is inelastically deformable into the closed position.
The distal extremity is preferably oriented such that its inner surface is at an angle of at most about 90xc2x0 relative to the outer surface of the clip body. The inner surface (or the entire distal extremity) may also be arcuate in shape. The distal extremity is usually tapered to a sharp point at its distal end to facilitate penetration of the graft and target vessel walls. One or more barbs may be provided near the distal end to maintain the graft and target vessel walls on the distal extremity.
The invention also provides an applier for applying the surgical clip. The applier includes a holding mechanism for releasably holding a surgical clip and a shaping mechanism for shaping the clip so as to compress the graft vessel wall against the target vessel wall. Although a variety of holding mechanisms are possible, in one embodiment the holding mechanism comprises a pin at the distal end of the applier, in which case the surgical clip includes a middle portion having an aperture for receiving the pin. Various types of shaping mechanisms are also possible, but in an exemplary configuration, the clip applier includes an inner shaft and an outer shaft axially movable with respect to each other. The clip is held by a first of the inner and outer shafts, and the clip body is shaped by engagement with a second of the inner and outer shafts. In a particularly preferred aspect, the clip applier is configured for endoscopic, laparaoscopic, thoracoscopic, or other minimally-invasive procedures, by holding the clip at the end of a small-profile elongated shaft suitable for positioning through a small incision, trocar sleeve, tubular port, cannula or the like. An actuator at the proximal end of the shaft permits remote application of the clip from outside the body cavity.
In another embodiment, the surgical clip of the invention comprises a clip body, a needle portion extending from the clip body that has a distal end configured to penetrated the graft and target vessel walls and to extend outside of the graft and target vessels. The clip body is configured to prevent its passage through the graft and target vessel walls so that it remains outside of the graft and target vessels. A retainer is further provided on the clip for retaining the graft and target vessel walls on the needle portion.
In one configuration, the retainer comprises a leg attached to the clip body and movable from an open position spaced apart from the needle portion to a closed position closer to the needle portion. The leg may be hingedly movable or inelastically deformable into the closed position. Preferably, the retainer is configured to compress the graft vessel wall against the target vessel wall for reliable hemostasis. The leg may also be configured to shield the distal end of the needle portion in the closed position.
Alternatively, the retainer may comprise a barb or other retention device on the needle portion itself. A plurality of barbs may be provided at spaced apart positions along the extremity of the needle portion so that the needle portion may be passed through the graft and target vessel walls a desired amount and the barbs will prevent the needle portion from backing out of the vessel walls. As an alternative to barbs, a retainer which is unidirectionally slidable or threadable onto the needle portion may be provided which is placed on the needle portion after it has been passed through the graft and target vessel walls., The needle portion is preferably hook-shaped, J-shaped or oriented at an angle of at least about 90xc2x0 relative. to the clip body so that the needle portion may be advanced through the vessel walls until its curved portion or the clip body engages the vessel wall. The barbs or other retaining devices are positioned relative to the clip body so as to maintain the graft vessel wall in compression against the target vessel wall.
In an additional embodiment, the surgical clips of the invention are configured to be coupled to a flexible ring-shaped band, which is preferably a continuous ring of suture, metal or plastic wire or strip, or other flexible material. The band defines a central opening through which the graft vessel may be received. Each clip has a first portion for engaging the graft vessel wall, and a second portion for engaging the target vessel wall, the first and second portions being configured to retain the graft vessel wall in sealing engagement with the target vessel wall. A plurality of clips are positionable at spaced-apart locations around the band. In this way, application of the clips to the vessels is accomplished by simply placing the band over the end of the graft vessel and applying each clip to the vessel wall. The graft vessel may then be positioned adjacent to the opening in the target vessel and each clip applied to the target vessel wall to create a sealed anastomotic connection. The band may be either left in place, or configured for removal by cutting or other wise detaching the ring from the clips.
Preferably, the clips are coupled to the band so as to be slidable to the desired position around the perimeter of the band. In one configuration, the clips have a loop or eyelet through which the band may be slidably received. The clips in this embodiment may have any of various configurations suitable for vascular anastomosis, including those described above, as well as other configurations not specifically described.
In a preferred embodiment, a method of joining a graft vessel to a target vessel according to the invention comprises providing a plurality of surgical clips each including a clip body having a distal extremity with a distal end and a proximal extremity with a proximal end; penetrating the graft vessel wall and the target vessel wall with the distal extremity of each surgical clip such that the distal and proximal ends are disposed outside of the graft and target vessels; and shaping a portion of each clip body outside of the graft and target vessels so as to compress the graft vessel wall against the target vessel wall with the graft lumen in communication with the target lumen. In this way, a robust, reliable and hemostatic anastomosis is provided which is simple and convenient to perform using only two hands, which minimizes the amount of foreign material in contact with the blood stream, which allows the surgeon to place each clip in the optimum location based on the size, shape and condition of the vessels, and which provides a degree of compliance in the completed anastomosis comparable to that of sutured anastomoses. The invention thus combines the ease of application, flexibility of position, reliability, and compliance of sutures, with the convenience and quickness of surgical clips.
Because of its simplicity and convenience, the invention is particularly well-adapted for use in endoscopic, laparoscopic, thoracoscopic and other minimally-invasive applications. The clips may be applied to a body structure using slender instruments positioned through percutaneous ports such as trocar sleeves, tubular cannulas, or small incisions, under direct visualization through such ports or under video-based visualization by means of an endoscope positioned through a port.
The nature and advantages of the invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings.